Hi I have a Pixhak 2.4.8 FC and I am trying to make my drone. I tested ESC and rotors separately with the transmitter and they are working but when I connected my FC rotors are not powered. I calberated everything using mission planner.
Can any body help me. I have seen many you tube videos but of no help.
Lalit
You are jumping over mandatory calibration steps and wondering why the flight controller is protecting you from yourself, and not letting you test the motors?
Follow the documented procedure, calibrate all sensors before trying to test the motors and ArduPilot will let you test them.
If you want to save time, and prevent errors like this one , use the ArduPilot methodic configurator software.
Is your safety switch configured? Does it work with the motor test tab? Have you set the outputs correctly?
And of course the safety switch must be in the right position 
For the Pixhawks the common safety switch that comes with it generally you need to hold it until it’s led goes would. This is proceeded by beeping sounds from the esc